The international chemical weapons watchdog charged with ridding Syria of its stockpile says it has received the last of the country's toxic chemicals identified for removal.

The head of the Organization for the Prohibition of Chemical Weapons, Ahmet Uzumcu, said at a news conference Monday in The Hague the ship carrying the last of the chemical weapons had just left the Syrian port of Latakia.

Uzumcu said it will take up to four months to destroy the 1,300 tons of chemicals declared to the organization.

Britain's Deputy ambassador to the United Nations, Peter Wilson, said this represents 'substantial progress,' but there are still 'procedural and factual discrepancies' with the Syrian declaration that need to be resolved.

Syrian President Bashar al-Assad agreed to destroy Syria's stockpile of chemical weapons under international pressure following the deaths of hundreds of people in a sarin gas attack last year on the outskirts of Damascus.

Western countries blamed Assad's forces for unleashing the nerve agent. The Syrian government blamed the rebels in Syria's civil war, which is now in its fourth year.